The lead author of this work, Fred (Wenshuo) Zhao, photographed in front of the Mendenhall Glacier in Juneau, Alaska. The logs at his feet, recently exposed by the retreating ice, are the subject of his undergraduate thesis and this publication. The College of Wooster Tree Ring Lab has an extensive collection of subfossil wood (trees run over in the past by glaciers) and this wood is often stained by exposure to the elements altering the color of the wood. This alteration inhibits the measurement of tree-ring parameters like blue intensity measurements. Measuring blue intensity (BI) has been shown to improve climate reconstruction and improve general tree-ring dating (Wilson et al, 2017, 2019). Fred, with the great help of Junpeng Fu and Nick Wiesenberg at Wooster, chemically treated the wood showing an improved climate signal in the BI measurements after treatment. This paper describes the process and evaluation of this chemical method using wood sampled from along the Gulf of Alaska as an example.
Degrees C
One of the clever tests that Fred performed to evaluate the improved climate signal was to compare climate signal of latewood blue intensity measurements before soaking in hydrogen peroxide (graph on the left) and after soaking (right)
https://woostergeologists.scotblogs.wooster.edu
The College of Wooster Tree Ring Lab faculty, staff and students have teamed up to publish results of an analysis of a network of tree-ring sites in Northeast Ohio to ask the question what is driving the changing climate response of the trees. The tree-ring sites include young (100-year-old) white oaks in Secrest Arboretum, Wooster, two sites of post-settlement age (about 200-years old) from Wooster Memorial Park and The Kinney Field Park both in Wooster and four old growth sites (>300 years old) from some of our favorite sites including The College of Wooster campus, Cornerstone Elementary, Browns Lake Bog, David Kline’s (the author) old growth forest on his farm and Johnson Woods the largest tract to old growth white oak forest in Ohio.
The upshot of the study reveals that the one- hundred-year-old white oak stand in Secrest Arboretum, along with two second growth stands have consistently responded positively to summer (June-July) precipitation over the past century, whereas the four nearby old growth sites have lost their moisture sensitivity since about the mid 1970s. This “fading drought signal,” which has been previously reported by Maxwell et al. (2016), appears to be more a result of the legacy of land use
https://woostergeologists.scotblogs.wooster.edu
Learning about environmental change from tree rings
